Resting & Action Potentials Flashcards
What are the four important properties of neurones?
Excitability, signal integration & propagation, signal transmission, plasticity
How were resting membrane potentials first studied?
Giant squid axon
At rest, which side of the axon membrane is negative?
Inside
What is the approximate resting potential of an axon?
-60mV
What causes leak current?
Selective permeability of the membrane to potassium ions
How are ion gradients maintained?
Ion pumps
What does Na+/K+ ATPase do?
Uses energy to move 3Na+ out of the cell and 2K+ into the cell
What does it mean for an enzyme to be electrogenic?
Generates a potential difference between the inside and outside of the cell
What does ouabain poison block?
Na+/K+ ATPase
In the Nernst equation, what is Ek?
Equilibrium potential of the ion (mV)
In the Nernst equation, what is R?
Gas constant
In the Nernst equation, what is T
Temperature (K)
In the Nernst equation, what is z?
Valence of the ion
In the Nernst equation, what is f?
Faraday constant
What does the Nernst equation do?
Compare electrical and chemical gradients to determine the electrochemical gradient
What can the Nernst equation be used to determine?
Direction of the ion at any given membrane potential
What is the Goldman constant field equation used for?
Determining the direction of multiple ions at any given membrane potential
In the Goldman constant field equation, what is Em?
Membrane potential
What temperature does the Goldman constant field equation relate to?
37C
What happens during depolarisation?
Vm approaches ENa, spike due to transient increase in PNa
What happens during repolarisation?
Vm approaches EK, spike due to transient increase in K
What was shown by Hodgkin and Katz?
K+ is more responsible for resting potential and Na+ is more responsible for action potential amplitude
